1. Field of the Invention
The present invention relates to a knocking writing utensil such as a ball-point pen, a mechanical pencil, or a marker, that uses a knocking operation to move a writing medium to a forward position in which the tip of the writing medium protrudes from the tip of an external cylinder.
2. Description of the Related Art
A conventional knocking writing utensil includes an external cylinder, a writing medium inserted and housed in the external cylinder so as to moved in the axial direction, an elastic body for urging the writing medium rearward, a clip with its proximal end fixed to the external cylinder, and a knock body that is exposed outwardly from the external cylinder to be easily knocked (e.g., actuated, depressed, etc.). The knock body is operated to move the writing medium from a withdrawn position within the external cylinder to a forward position where the writing medium tip protrudes from the tip of the external cylinder.
If a user forgets to withdraw the writing medium into the external cylinder and clips the conventional writing utensil to the edge of the user's jack pocket for instance, then the writing medium may stain the user's clothing or make a hole therein.
A knocking writing utensil that solves this problem is described in the assignee's Japanese Utility Model Publication No. 5-25915 and Japanese Utility Model Publication No. 6-15735.
In these knocking writing utensils, a clip is integrated with a knock body protruding from the rear and portion of an external cylinder. An engagingly-locking protrusion is provided on the rear surface of the tip of the clip so as to engage an engaging-lock receiving portion formed on the external cylinder to hold a writing medium at a forward position.
In this knocking writing utensil, when the user attempts to separate the tip of the clip from the external cylinder, in order to insert the clip on a pocket, the engagingly-locking protrusion is disengaged from the engaging-lock receiving portion to automatically withdraw the writing medium. This prevents a garment, and an attached pocket, from being stained or damaged. However, since the clip moves in response to the knocking of the knock body, knocking the knock body is impossible while the clip is in a gripping position. Thus, with this type of writing utensil, a knocking operation is difficult.
Furthermore, to return the writing medium to the withdrawn position, both ends of the clip may be rocked up and down, and the knocking operation of the knock body does not allow the writing medium to return to its housed (withdrawn) position. Thus, different operations are required to extend the writing medium and to withdraw it. Therefore, another problem is that the operation of withdrawing the writing medium and the knocking operation are not simple, but instead are unduly complicated.